1. Field of the Invention
The present invention generally relates to coaxial speaker units, and particularly relates to a coaxial speaker unit in which dust is prevented from entering a central portion of a low-frequency band magnetic circuit of the coaxial speaker unit.
2. Description of the Prior Art
In most conventional speaker units, as shown in FIG. 4, a mount 9 is provided on a low-frequency band magnetic circuit 1, a high-medium frequency band magnetic circuit 2 is provided on the mount 9, and diaphragms 3 and 4 are provided for the magnetic circuits 1 and 2 respectively, with a gap formed between an upper surface of the low-frequency band diaphragm 3 and a lower surface 2A of the high-medium frequency band magnetic circuit 2. A voice coil 5 is wound on a bobbin 6 of the low-frequency band diaphragm 3. In order to close the above-mentioned gap, a ring 7 is fixed on an upper end surface, in the drawing, of the bobbin 6 and a cylindrical dust-proof member 8 is adhesively fixed between the ring 7 and the lower surface 2A of the low-frequency band magnetic circuit 2.
In the coaxial speaker unit as described above, there has been a problem in that the ring 7 serving as the attachment seat for the dust-proof member 8 must be provided on the bobbin 6 of the voice coil 5, resulting in an increase in assembly costs as well as greater weight of the bobbin 6, thus lowering speaker sensitivity.